Tobacco-specific nitrosamines (TSNAs), such as N-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), can be found in smokeless tobacco; mainstream smoke; and side stream smoke of cigarettes. It has been reported that air-cured and flue-cured tobacco contain tobacco-specific nitrosamines. See, “Effect of Air-Curing on the Chemical Composition of Tobacco”, Anna Wiernik et al., Recent Adv. Tob. Sci, (1995), 21: 39-80. According to Wiernik et al., TSNAs are not present in significant quantities in growing tobacco plants or fresh cut tobacco (green tobacco), but are formed during the curing process. Bacterial populations which reside on the tobacco leaves are stated to largely cause the formation of nitrites from nitrate during curing and possibly effect the direct catalysis of the nitrosation of secondary amines at physiological pH values. The affected secondary amines include tobacco alkaloids, which form TSNAs when nitrosated.
Because curing of tobacco leaves is normally performed by the farmer who grows the tobacco, a simple, economical and non-labor-intensive method of reducing TSNA levels in the cured tobacco leaves is desirable.